I don't know of any way to map it to keyboard at present. VR has stated that they intend to do a significant overhaul of the UI at some point, which will involve dedicating a Dev to it full time for a period. Thus it wasn't very high on the priorities list the last time they addressed it. I've never heard them specifically mention camera control.
One of my biggest personal hopes is to have every UI function be mappable to the keyboard and not just restricted to the mouse. I encourage you to ask your question in a Q&A, or in a stream if you watch them live. Let them know what's important to you.